Out of the approximately 20,000 species of butterflies around the world, 275 species reside in Canada, and each has their own way of making it through our cold winters. With an average lifespan of one month or less for most butterflies, monarchs and morning cloaks are a couple of species that are the exception. They can live up to nine months. But, a butterflies life is fraught with danger, between predators, disease, and accidents with vehicles, the life of a wild butterfly isn’t easy.
These delicate creatures are tougher than many give them credit for and have managed to adapt to winter survival through various methods.
Overwintering
Butterflies all go through the same life cycle: egg, caterpillar, pupa in a chrysalis and butterfly, where they differ is in their taste of host plants and their methods of overwintering. Species overwinter in different stages of their lifecycle.
Many butterflies are winter residents and spend the season as caterpillars, while others remain as pupae and a rare few overwinter as eggs. A select number may spend the winter as adults hibernating in notches in trees or other sheltered locations. The monarch look-a-like, the viceroy, spends the winter hibernating as a caterpillar nestled in the fallen leaves of willow or poplar trees. Eastern and black swallowtails hibernate as pupa within their chrysalis when the days become colder and emerge in the spring, adults do not survive the cold. One of the few butterflies that hibernates in its adult form is the mourning cloak. These butterflies will find crevices in trees to wait out the weather and are often one of the first butterflies we see in the spring.
Migration
In addition to the monarchs several other butterflies, including the painted lady, American lady, and red admiral, migrate to more southerly locations including the southern United States and Mexico. Butterflies migrate for many reasons including the loss of their food sources and the fact that they are cold-blooded insects that cannot withstand the falling temperatures. Often butterfly migration is not noticed by people as many do not tend to fly in large groups. However, mourning cloaks, monarchs and a few other species have been known to migrate in this manner, often with thousands of butterflies making the trek south together.
Monarchs are the most studied and researched migratory butterfly. Their gorgeous colour, amazing ability to fly such a long distance and recent declining numbers have brought this beauty into the public eye. Still, much is not known. How do they know where to fly? How do millions find the same overwintering sites, in many cases the same tree, when they aren’t the same butterflies that were there the prior year? How are these fragile creatures able to endure flights up to 2,500 miles away? Much is unknown, but research is ongoing in the patterns and locations of butterfly migration.
As previously published for Manitoba, Alberta and Ontario Gardener magazines. Visit localgardener.net
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